1. Field of the Invention
This invention relates to cementitious compositions having improved fluidity and dispersability by virtue of the addition of an effective amount of an ester derived from a polyoxyethylene glycol and a polycarboxylic acid which is a polymeric fatty acid or polycarboxylic adduct acid.
2. Description of the Prior Art
It is known that it is possible to obtain cement compositions which are readily workable and which have acceptable flow by adding an amount of water in excess of that required to hydrate the cement. It is, however, equally well established that the strength of the concrete mixture after setting is decreased if excess water, i.e. an amount of water above that required for the setting reaction, is employed.
Additives have therefore been developed to improve the flowability and workability of concrete compositions. These additives, sometimes referred to as water reducers, plasticizers, or superplasticizers, make it possible to obtain concrete compositions having the desired consistency at much reduced water levels. As a result of the reduction in water content, the resulting hardened concrete mixtures have improved strength. Additionally, in many cases the additives facilitate dispersion of the cement with the water. Typical additives for this purpose include lignin sulfonates, sulfonates of melamine-formaldehyde condensates, sulfonates of naphthalene-formaldehyde condensates, sulfonated styrene polymers, saponified styrene-maleic acid copolymers and the like.
U.S. Pat. No. 4,746,367 describes improved superplasticizers compositions comprising sulfonated copolymers of styrene and .alpha.-methyl styrene or salts thereof.
U.S. Pat. No. 4,655,838 discloses cement additives which improve flowability and workability and which are mixtures of a saponified copolymer of styrene and maleic acid or half-esters thereof with one or more agents selected from the group consisting of a salt of a condensation product of naphthalene sulfonic acid with formaldehyde, a salt of a condensation product of an alkylnaphthalene sulfonic acid with formaldehyde, a salt of a condensation product of naphthalene sulfonic acid and an alkylnaphthalene sulfonic acid with formaldehyde, a salt of a condensation product of naphthalene sulfonic acid and lignin sulfonic acid with formaldehyde, a salt of lignin sulfonic acid, sulfonated condensation products of melamine with formaldehyde, saponified products of a sulfonated copolymer of styrene and maleic acid, a salt of a condensation product of a sulfonated creosote oil with formaldehyde and a salt of a condensation product of a sulfonated heavy aromatic hydrocarbon oil with formaldehyde.
U.S. Pat. 4,164,426 discloses the use of zinc naphthalene-formaldehyde sulfonate as a superplasticizers for concrete compositions.
Sulfonated polystyrene and salts thereof are disclosed as a plasticizers for hydraulic cement compositions in British Patent No. 1,588,130.
U.S. Pat. No. 3,686,133 discloses the use of salts of naphthalene sulfonic acid-formaldehyde condensation products and salts of gluconic acid in hydraulic cements to obtain better flow properties and improve the strength.